nginx, and pound are two widely used web load balancers. You should be able to find plenty of blog posts and write-ups with sample configs for setting those two

nginx, and pound are two widely used web load balancers. You should be able to find plenty of blog posts and write-ups with sample configs for setting those two up. For databases, at least with MySQL, you should setup a master -> slave(s) setup to send reads to slaves and writes to master. If you have many slaves, you can configure your DB classes to randomly select DB servers, or you can setup a TCP load balancer using something like HAProxy to load balance the slaves.